Exchangeable Process Unit

ABSTRACT

The invention relates to a device and to a method for producing 3D moulded parts using at least one process unit, also suitable for a large scale production in series of 3D moulded parts such as foundry cores and moulds and other articles which are required in large amounts.

The invention relates to a device and to a method for producing 3Dmolded parts using at least one process unit, also suitable for largescale series production of 3D molded parts such as foundry cores andmolds and other articles which are required in large quantities.

European Patent EP 0 431 924 B1 describes a process for producingthree-dimensional objects based on computer data. In the process, a thinlayer of particulate material is deposited on a platform by means of acoater (recoater) and has a binder material selectively printed thereonby means of a print head. The particulate region with the binder printedthereon bonds and solidifies under the influence of the binder and,optionally, an additional hardener. Next, the construction platform islowered by one layer thickness or the coater/print head unit is raisedand a new layer of particulate material is applied, the latter alsobeing printed on selectively as described above. These steps arerepeated until the desired height of the object is achieved. Thus, theprinted and solidified regions form a three-dimensional object (moldedpart).

Upon completion, the object made of solidified particulate material isembedded in loose particulate material, from which it is subsequentlyfreed. For this purpose, a suction device may be used, for example. Thisleaves the desired objects, which are then further cleaned to remove anyresidual powder, e.g. by brushing it off.

Other powder-based rapid prototyping processes, e.g. selective lasersintering or electron beam sintering, work in a similar manner, alsoapplying loose particulate material layer by layer and selectivelysolidifying it using a controlled physical source of radiation.

In the following, all these processes will be summarized by the term“three-dimensional printing method” or “3D printing method”.

Some of these methods use different coating options. In some methods,the particulate material required for the entire layer is placed infront of a thin blade. The latter is then moved over the constructionarea, spreading the material placed in front of it and thereby smoothingit. Another type of layer application consists in continuously placing asmall volume of particulate material in front of the blade as it moves.For this purpose, the blade is usually mounted to the underside of amovable silo. Directly above or next to the blade, an adjustable gap isprovided through which the particulate material can flow out of thesilo. The flow is stimulated by introducing oscillations into thesilo/blade system.

Subsequently or during the application of the layer, selectivesolidification follows by means of liquid application and/or exposure toradiation. In many cases it is necessary for the quality of the printthat the distance of the moving printing device to the current layerplane be as constant as possible.

The parts are usually present in a construction container afterprinting. In most cases, said construction container constitutes acuboid volume. The volume is charged with a wide variety of geometriesso as to make efficient use of the machine.

Some prior art printers have construction containers which can beremoved from the system and are also referred to as job boxes orconstruction containers. They serve as boundaries for the powder,thereby stabilizing the construction process. Changing the constructioncontainer allows the process steps to be carried out in parallel, thusmaking efficient use of the system. There are also systems which involveprinting on a platform which can be removed from the system, just likethe construction container. Methods are also known which involveprinting on a continuous conveyor belt at a certain angle. Theaforementioned machine features allowed to make construction processesmore economical and help reduce downtime. However, well-known 3Dprinters still have the disadvantage that considerable downtimes of themachines mean a suboptimal degree of utilization.

3D printing on the basis of pulverulent materials and introduction ofliquid binders is the quickest method among the layer constructiontechniques. This method allows the processing of different particulatematerials, including—as a non-exhaustive example—natural biological rawmaterials, polymeric plastic materials, metals, ceramics and sands.

The different parts of the system exhibit different degrees of wear.Depending on the type of pulverulent material, e.g. all conveyingequipment, blades, seals and lines in contact with the powder aresubject to specific abrasion. This can lead to process-relevantequipment such as a coater blade, whose geometric shape is veryimportant for the layer application result, having to be replaced atregular intervals in order to prevent an intolerable drop in quality oreven failure of the system part. The same applies to the print head,whose nozzles are also subject to wear, which can lead to a drop in theperformance of the respective nozzle on the one hand and total failureon the other. The print heads usually have a large number of nozzles.The nozzles are usually located next to each other in a so-called nozzleplate. For 3D printing, it is tolerable in most cases if individualnozzles of a print head have failed. However, if the failure affects alarger number of nozzles or if a majority of nozzles are affected thatare directly next to each other, it is necessary to replace the printhead.

It is important here that the nozzles have the same distance to theconstruction field when printing the binder. If this is not the case,undesired deviations of the print image from the calculated layer imagemay occur. In order for the distance to remain the same, the print headmust be moved parallel to the plane of the construction field whensweeping over the latter during printing and the nozzle plate must beparallel to the plane of the construction field.

The same applies to any built-in radiation sources for hardening orheating the powder. These sources must also be arranged parallel to theconstruction field plane and move parallel to said plane in order toensure uniform energy input.

The construction field plane, on the other hand, is determined by thecoating blade in contact with the powder and by the coating blade'straversing axis.

Now, if one or more of the components (coating blade, print head orradiation source) is replaced, the spare parts and their receptaclesmust either be manufactured so precisely that the required parallelalignment is restored, or there must be devices on one of the twoelements that allow them to be adjusted to each other.

Usually, the manufacturing accuracy of the parts is not sufficient tomeet the accuracy requirements mentioned. For this reason, replacing oneof the components requires the system to be switched off for theduration of the replacement and readjustment. Depending on the type ofsystem, this can require several hours of system downtime. In addition,the work must be performed directly on the system by an experiencedtechnician.

European patent application EP 2 214 889 A1 describes a device for a 3Dprinter that has a mounting platform on which all traversing devices,including the Z-axis, are mounted. The advantage of such an approach isthe achievement of high process accuracy through manufacturing precisioncombined with less adjustment effort. In addition, the required accuracyis taken out of device parts that are more difficult to machine, such asthe frame. In terms of simplified maintenance and increased availabilityof the device, this approach does not provide any advantages, sincereplacing the mounting platform with all connections and units isextremely complex. The presently described invention according to thepresent disclosure is not only novel, but also inventive over this priorart document.

The aforementioned downtimes of 3D printing systems imply significanteconomic disadvantages and especially for 3D printing systems or systemlines that are designed to achieve a high production throughput, theaforementioned downtimes are problematic or even incompatible with therequired production targets.

Also, in many cases 3D printing machines cannot be integrated intoseries production because they require excessively long downtimes formaintenance work.

It is therefore an object underlying the application to provide a devicewith which it is possible to exchange functional parts of a 3D printingmachine, such as coater, print head or radiation source, on the 3Dprinter in a short time.

A further object underlying the application is to provide a device whichhelps to avoid the need for adjusting the functional parts in the 3Dprinting machine.

It is a further object underlying the application to provide a 3Dprinting machine that can be integrated into system lines and that ischaracterized by reduced downtimes for maintenance work or generallyrequires only low downtimes.

BRIEF SUMMARY OF THE DISCLOSURE

In one aspect, the disclosure relates to an exchangeable function unitsuitable for a 3D printing method, said function unit comprising orconsisting of at least two functional units comprising at least onematerial application means for applying a particulate material and/orfluid and at least one means for selectively solidifying the appliedmaterial, and optionally having further layer treatment means, whereinthe functional units are each single, double, triple or multiple, andwherein the functional units are mechanically connected to each otherdirectly or by a connecting means.

In another aspect, the disclosure relates to a method for exchanging afunction unit in a 3D printing machine by moving an exchangeablefunction unit as described above into and out of the machine.

In another aspect, the disclosure relates to a 3D printing machinesuitable for the exchangeable function unit as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B: illustration of different types of exemplaryexchangeable function units according to the disclosure.

FIG. 2 : schematic view of the fastening and supply options of anexchangeable function unit according to the disclosure.

FIG. 3 : schematic view of an operational exchangeable function unit inits target position according to the disclosure.

FIG. 4 : schematic view of an insertion opening with closure meansaccording to the disclosure.

FIGS. 5 and 6 : schematic illustration of the layer construction processby means of various exchangeable function units according to thedisclosure.

FIGS. 7-9 show the above-described embodiments of the arrangement of theexchangeable function unit on a gantry by means of 4 combined receivingand securing means.

FIGS. 10 to 12 show a further embodiment of the quantity and arrangementof the receiving and securing means.

FIGS. 13 and 14 show an embodiment of the invention in which thereceiving means and securing means of the exchangeable function unit aredesigned separately from one another.

DETAILED DESCRIPTION OF THE DISCLOSURE

In the following, several terms will be defined more precisely.Otherwise, the terms used shall have the meanings known to the personskilled in the art.

In the sense of the disclosure, “layer construction methods” or “3Dprinting methods”, respectively, are all methods known from the priorart which enable the construction of parts in three-dimensional moldsand are compatible with the process components and devices furtherdescribed herein.

As used in the disclosure, “binder jetting” means that powder is appliedin layers onto a construction platform, one or more liquids is/areprinted on the cross-sections of the part on this powder layer, theposition of the construction platform is changed by one layer thicknesswith respect to the previous position, and these steps are repeateduntil the part is finished. In this context, binder jetting also refersto layer construction methods that require a further process componentsuch as layer-by-layer exposure, e.g. with IR or UV radiation, andmethods that are also referred to as high-speed sintering.

A “molded article” or “part” or “3D molded part” or “3D part” in thesense of the disclosure means all three-dimensional objects manufacturedby means of 3D printing methods and exhibiting dimensional stability.

“3D printer” or “printer” as used in the disclosure means the device inwhich a 3D printing method can take place. A 3D printer in the sense ofthe disclosure comprises a means for applying construction material,e.g. a fluid such as a particulate material, and a solidification unit,e.g. a print head or an energy input means such as a laser or a heatlamp. Other machine components known to the person skilled in the artand components known in 3D printing are combined with theabove-mentioned machine components in individual cases, depending on thespecific requirements.

A “construction field” is the plane or, in a broader sense, thegeometric location on or in which a particulate material bed growsduring the construction process by repeated coating with particulatematerial. The construction field is frequently bounded by a bottom, i.e.the “construction platform”, by walls and an open top surface, i.e. theconstruction plane.

As used in the disclosure, “process unit” or “function unit” refers to ameans or a component using which the result of the processes of coatingand selective solidification can be realized; this may include coater(recoater), print head, nozzles, laser unit, heat source, UV lightsource or/and further layer treatment means.

The process of “printing” or “3D printing” in the sense of thedisclosure summarizes the operations of material application, selectivesolidification or imprinting and working height adjustment and takesplace in an open or closed process chamber.

A “receiving plane” in the sense of the disclosure means the plane ontowhich the construction material is applied. In accordance with thedisclosure, the receiving plane is always freely accessible in onespatial direction by a linear movement.

A “traversing axis” in the sense of the disclosure is an axis whichcarries a process unit or which can be produced along the latter, isarranged above the construction field tools and has a long travelcompared to the other axes in the system. “Traversing axis” may alsoindicate the direction in which, for example, a construction field toolis synchronized and can be moved in coordination with other deviceparts. A print head can also be moved on a “traversing axis”.

“Construction field tool” or “functional unit” in the sense of thedisclosure refers to any means or device part used for fluidapplication, e.g. particulate material, and selective solidification inthe production of molded parts. Thus, all material application means andlayer treatment means are also construction field tools or functionalunits.

According to the disclosure, “spreading out” means any manner in whichthe particulate material is distributed. For example, a larger quantityof powder may be placed at the starting position of a coating pass andmay be distributed or spread out into the layer volume by a blade or arotating roller.

As the “construction material” or “particulate material” or “powder” inthe sense of the disclosure, all flowable materials known for 3Dprinting may be used, in particular in the form of a powder, slurry orliquid. These may include, for example, sands, ceramic powders, glasspowders and other powders of inorganic or organic materials, such asmetal powders, plastic materials, wood particles, fiber materials,celluloses or/and lactose powders, as well as other types of organic,pulverulent materials. The particulate material is preferably afree-flowing powder when dry, but a cohesive, cut-resistant powder mayalso be used. This cohesiveness may also result from adding a bindermaterial or an auxiliary material, e.g. a liquid. The addition of aliquid can result in the particulate material being free flowing in theform of a slurry. Synthetic resins such as epoxides or acrylates canalso be considered as construction materials in the sense of thedisclosure. In general, particulate materials may also be referred to asfluids in the sense of the disclosure.

The “surplus quantity” or “overfeed” is the amount of particulatematerial which is pushed along in front of the coater during the coatingpass at the end of the construction field.

“Coater” or “recoater” or “material application means” as used in thedisclosure refers to the unit by means of which a fluid is applied ontothe construction field. The unit may consist of a fluid reservoir and afluid application unit wherein, according to the present invention, thefluid application unit comprises a fluid outlet and a “coating knifedevice”. Said coating knife device may be a coating blade. However, anyother conceivable, suitable coating knife device may be used. Forexample, rotating rollers or a nozzle are conceivable as well. Materialcan be fed via reservoirs in a free-flowing manner or via extruderscrews, pressurization or other material conveying devices.

The “print head” or means for selective solidification in the sense ofthe disclosure usually consists of various components. Among otherthings, these can be printing modules. The printing modules have a largenumber of nozzles from which the “binder” is ejected as droplets ontothe construction field in a controlled manner. The print modules arealigned with respect to the print head. The print head is aligned withrespect to the machine. This allows the position of a nozzle to beassigned to the machine coordinate system. The plane in which thenozzles are located is usually referred to as the nozzle plate. Anothermeans of selective solidification can also be one or more lasers orother radiation sources or a heat lamp. Arrays of such radiationsources, such as laser diode arrays, can also be considered. It ispermissible in the sense of the disclosure to implement selectivityseparately from the solidification reaction. Thus, a print head or oneor more lasers can be used to selectively treat the layer and otherlayer treatment means can be used to start the solidification process.An example of this would be printing on the layer with UV reactiveresins, which are then solidified via a UV light source. In anotherembodiment, an IR absorber is printed on the particulate material,followed by solidification using an infrared source.

“Layer treatment means” in the sense of the disclosure refers to anymeans suitable for achieving a certain effect in the layer. This may bethe aforementioned units such as print heads or lasers, but also heatsources in the form of IR emitters or other radiation sources such as UVemitters, for example. Means for deionization or ionization of the layerare also conceivable. What all layer treatment means have in common isthat their zone of action is distributed linearly over the layer andthat, like the other layering units such as the print head or coater,they must be guided over the construction field to reach the entirelayer.

“Actuators” in the sense of the disclosure are all technical means whichare suitable for triggering the movement of layer treatment meansrelative to one another within an exchangeable function unit, or forcarrying out movements of individual parts or components within thelayer treatment means.

“Insertion opening” as used in the disclosure means the area on a 3Dprinting machine where the exchangeable function unit is inserted intoand removed from the 3D printing machine for replacement; this insertionopening may be open or may be closable by suitable means such as aclosure or a closable flap. Opening and closing can be done with aseparate control; or, by retracting and extending the exchangeablefunction unit, the closure is automatically opened and closed again.There may also be some kind of barrier at the insertion opening, such asa slitted film or bristles, through which the exchangeable function unitcan be pushed.

A “suitable receiving means” in the sense of the disclosure is a meansarranged at the target position that assists in the positioning andproper functioning of the exchangeable function unit at the targetposition. Thus, the positional tolerance of an exchangeable functionunit within the 3D printing machine is defined by a suitable receivingmeans, and thus also the positional tolerance of the layer treatmentmeans with respect to the construction field.

In the sense of the disclosure, “lifting means” refers to a suitablemeans by which the extended exchangeable function unit is picked up andmoved away from the 3D printing machine, or by which the exchangeablefunction unit is lifted and moved towards the 3D printing machine and bywhich the exchangeable function unit is inserted into the 3D printingmachine. According to the disclosure, this can be a lift truck, a crane,a special tool or an industrial robot.

The “retraction” or “extension” of the exchangeable function unit in thesense of the disclosure is the process in which an exchangeable functionunit located in the 3D printing machine is released from its positionand is moved out of the 3D printing machine and a newly pre-adjustedexchangeable function unit is moved into the 3D printing machine andpreferably fixed at its target position. The retraction and extension ofthe exchangeable function unit can take place in one direction, e.g.from one side or from above in relation to the construction plane,moving to the target position in a direct line. However, the retractionand extension can also take place in the form of an arc movement or as aswivel movement in the 3D printing machine at 45° to 90° into or out ofthe 3D printing machine. The retraction and extension of the functionunit can be done manually or automatically. To ensure that the functionunit is not damaged during retraction or extension when exchanging itmanually, it may be useful to guide the movement via suitable means.This can be done, for example, using linear guides that are eitherpermanently installed in the machine or on the lifting means, or onother auxiliary devices. When the function unit is exchangedautomatically, it may be useful to have a suitable receptacle for anindustrial robot on the function unit. The robot then grips the functionunit through the opening in the system and guides it in a suitablemovement out of the 3D printer to a tray, if provided. Another functionunit is then placed on another defined tray, which can now be gripped inturn by the robot and moved into position in the 3D printer.

The retraction and extension of the function unit can also take place insuch a way that the function unit is retracted moved into a transportdevice when it is extended. This minimizes the time during which thefunction unit is in an undefined position and exposed to harmfulinfluences. The lifting means and the function unit can also be guidedby the transport device. The function unit is moved into the 3D printingmachine in reverse order directly from the transport device, which isplaced in the correct position on the 3D printing machine.

A “transport device” in the sense of the disclosure is a suitable meanswhich protects the exchangeable function unit and/or the layer treatmentmeans from harmful external influences, e.g. mechanical damage orcontamination, during transport to and from the 3D printing machine bymeans of the lifting means usually available in an industrialenvironment. The transport device can preferably be embodied such thatstorage of the process unit within the transport device is made possibleover a longer period of time without degradation or damage to theexchangeable function unit and/or the layer treatment means occurringdue to storage time. Again preferably, the transport device can beembodied such that several transport devices can be stacked for storingseveral exchangeable function units.

“Adjustment devices” in the sense of the disclosure are means by whichthe functional units of the exchangeable function unit can be presetwith respect to their position and alignment relative to each other insuch a way that, after insertion of the exchangeable function unit, allfunctions of the 3D printing process can be performed in the desired andcorrect manner and no further readjustment is required in the 3Dprinting machine. For example, in a layer construction process withselective solidification using a print head and binder application, itis possible to preset the application angle of the print head nozzlesand the application angle of the coater unit (recoater) and, ifnecessary, the recoater blade. In laser sintering, for example, theoptics, the diode array and the ion laser can be aligned to the coaterusing an adjustment device. Likewise, in this device other layertreatment means can also be adjusted with respect to the aforementioneddevices. The adjustment devices can be permanently mounted on eachfunction unit or can be used separately if required. Any means forsetting an exact position, such as a fine thread, is suitable as anadjustment device. An adjustment device preferably also has suitablemeasuring means to check the adjusted position of the respective layertreatment means. These measuring means can be, without restriction, e.g.mechanical or optical sensors. The measuring means can also bepermanently installed on each functional unit or used separately ifrequired.

“Kinematics” in the sense of the disclosure are all technical meanswhich are suitable for defining, guiding, tolerating and/or limiting therelative movement of layer treatment means with respect to one anotherwithin an exchangeable function unit or the relative movement ofindividual parts or assemblies to one another within the layer treatmentmeans.

“Securing means” as used in the disclosure refers to any means suitablefor temporarily securing the position of the exchangeable function unitin the 3D printing machine, such as a clip or a jaw or a plurality ofquick release fasteners, magnets, snap fasteners, zero point clamps orelectromagnetic fasteners. With a suitable choice of acceleration forcesfor the traversing movement during layer generation in the 3D printer,the weight force can also be a suitable securing means. In addition, thesecuring means are selected and designed in such a way that the locationand position of the exchangeable function unit in relation to the 3Dprinter is clearly defined and found with repeatable accuracy. To ensurethat this is also the case at different temperatures, appropriatemeasures for length compensation must be provided.

“Connecting means” in the sense of the disclosure may be rails, framesor other parts by which the functional units of the exchangeablefunction unit are connected to each other and arranged in their threedimensions, and which may optionally also serve to support theretraction and extension of the interchangeable function unit into andout of the 3D printing machine. In a specific embodiment, the functionalunits can also be directly connected to each other and, in addition,means intended for retracting and extending the exchangeable functionunit can be attached to the latter. Preferably, the connecting means aredesigned in such a way that the individual functional units are easilyaccessible in order to adjust their position or exchange them.

“Closure means” within the meaning of the disclosure is any means usedto close the insertion opening for the exchangeable function unit, e.g.a flap, door, slide, row of brushes, etc.

“Supply” in the sense of the disclosure is the supply of energy,construction material or other media such as, for example, compressedair or cooling water to the individual functional units. The supply ispreferably configured for quick coupling by suitable measures. Thecoupling preferably takes place at a common coupling position in theform of a coupling strip or a coupling block. The supply can preferablybe coupled without additional manual interaction, e.g. only by moving itin and out.

For the purposes of the disclosure, “preset” means that the functionalunits contained in the exchangeable function unit are aligned in termsof location and position such that simply moving them to the targetposition, using the securing means and establishing the supply issufficient to enable the 3D printing machine to be returned to operationimmediately after such movement, without substantially requiring anyadjustment or readjustment or any setting in relation to theexchangeable function unit.

“Target position” in the sense of the disclosure is the position in the3D printing machine up to which the exchangeable function unit isinserted and at which it is preferably fixed with the securing means.

“Removal position” as used in the disclosure means the location in the3D printing machine at which the function unit must be located in orderto extend it from the machine. Accordingly, the control of the 3Dprinter has a command upon which the exchangeable function unitapproaches the removal position with sufficient accuracy.Advantageously, this position is above the construction field. Even moreadvantageously, the removal position is approximately in the middleabove the construction field. The two possible end positions of theexchangeable function unit are less suitable, as the maintenance unitsfor the construction field tools are usually located there and thesecould be damaged during retraction or extension. When exchanging thefunction unit, the construction field tools should advantageously not bein engagement with a current layer. This can be ensured, for example, bylowering the construction platform by an appropriate amount beforehand.This process can also be stored in the control system so that thelowering of the construction platform and the movement to the removalposition takes place as a combined sequence in preparation for thereplacement of the function unit.

An object underlying the application is achieved by a production device,e.g. a 3D printing device, whose construction field tools, i.e. in thecase of a 3D printing device, the functional units needed for theprinting process, are connected to one another and arranged in such away that they can be removed together from the device while maintainingtheir alignment with one another and with the device, or the correctalignment of the functional units can be set before installation.

Furthermore, an object underlying the application is achieved in that asecond arrangement of construction field tools can be inserted into thedevice, adjusted to each other and connected to the device in the sameway, so that the production process can be continued in the same way.

Furthermore, an object underlying the application is achieved in thatauxiliary means are also provided for changing the construction fieldtools, said auxiliary means allowing the device to be exchanged quicklyand put back into operation in short order.

Furthermore, an object underlying the application is achieved by amethod that uses the devices provided by the production device or theexchangeable function unit.

Furthermore, an object underlying the application is achieved, inparticular, by an exchangeable function unit suitable for a 3D printingmethod, said functional unit comprising or consisting of at least twofunctional units comprising at least one material application meansand/or smoothing means for applying and/or smoothing a fluid and atleast one means for selectively solidifying the fluid, and optionallycomprising further layer treatment means, wherein the functional unitsare each single, double, triple or multiple, and wherein the functionalunits are mechanically connected to each other directly or by aconnecting means.

With the device according to the invention, it is advantageouslypossible to reduce or avoid the downtimes of 3D printing machines causedby maintenance work or the necessary replacement of parts or functionalcomponents that are susceptible to wear. Thus, the machine running timecan be increased and it becomes possible to integrate one or more 3Dprinting machines equipped with such exchangeable function units into anassemblage of other production systems, e.g. in series production, e.g.in vehicle construction.

The invention thus makes it possible for the first time to integrate 3Dprinting machines into substantially fully automated productionprocesses.

Previously, certain 3D printed parts had to be pre-produced and theseparts could be a time-limiting factor in other production processes. Inaddition, storage and delivery involved organizational effort and costs.

The invention makes it possible to produce 3D molded parts directly onsite and integrated into other semi-automated or fully automatedmanufacturing processes. This makes it possible to simplify complexmanufacturing processes.

A further advantage is that machine availability per se is increased andthus a further increase in the actual and economic degree of utilizationof 3D printing machines equipped with exchangeable function unitsaccording to the invention can be achieved.

The invention thus advantageously contributes to further automation of3D printing processes per se as well as other manufacturing processesand types of series production using 3D printing processes.

Furthermore, due to the coupling of the print head and the coater in afunction unit in an embodiment according to the present disclosure, thesteps of particulate material application and selective solidificationcan be carried out when the exchangeable function unit passes over theconstruction field. If there is a recoater on both sides of the printhead, or if there is a unit comprising a recoater and print head foreach direction of travel, both steps can be carried out in each of thetwo directions of travel, thus accelerating the coating speed and themolded part build-up. This essentially halves the time required toproduce the molded parts compared to a 3D printing machine that onlyperforms both steps in one direction at a time.

Furthermore, the exchangeable function unit according to the inventionachieves a decoupling of the adjustment of the functional units andtheir installation in the 3D printing machine. The invention alsoachieves many process and cost advantages, as the adjustments of theparts to be replaced can now be made outside the 3D printing machine.

In further aspects, the exchangeable function unit according to thedisclosure is characterized in that the material application and/orsmoothing means is at least one of a recoater, an extruder or a coatingknife, the selective solidification means is an inkjet print head,nozzles, a radiation source and/or an energy source, the fluid is aparticulate material or a liquid or mixtures of both, that an optionallayer treatment means is selected from radiation sources and/or energysources and application means for gases or liquids, that the connectingmeans is one or more connecting rails, a frame, a connecting grid or aconnecting plate.

The exchangeable function unit disclosed herein is provided for a 3Dprinting machine and has further advantageous embodiments, wherein thefunction unit is retractable into and extendable out of a device for 3Dprinting and wherein the function unit or the layer construction devicehas at least one suitable receiving means and/or securing means by whichthe function unit is positionable in the 3D printing device.

The exchangeable function unit disclosed herein may have suitablereceiving means and/or securing means and these are preferably one ormore quick release fasteners, magnets, snap fasteners, zero point clampsor electromagnetic fasteners.

A major advantage of the exchangeable function unit disclosed herein isthat it can be preset and pre-adjusted outside the 3D printing machine.Advantageously, the functional units can be preset in position to eachother and to the 3D printing device.

Another advantage is the shortened downtime in cases of maintenance orfailure and replacement of a layer treatment means due to the quickexchange of the function unit.

The position of the exchangeable function unit disclosed herein can bepreset using one or more adjustment devices or manufacturing tolerances.

The functional units can be connected directly to each other as anexchangeable function unit or via connecting means. In particular, it isadvantageous if one, several or all of the material application meansand layer treatment means are designed to be movable relative to oneanother on the connecting means.

In an exchangeable function unit as disclosed herein, the actuators andkinematics required for the relative movement of the materialapplication means and/or layer treatment means can be integrated intothe function unit and the energy required for the movement can besupplied to them by the 3D printing device.

In a further aspect, the disclosure relates to a 3D printing devicecomprising an exchangeable function unit as described above, aninsertion opening optionally comprising one or more baffles or/andrails, and further known means of a 3D printing device optionallyselected from the group consisting of conveying means, material supplymeans and/or material removal means.

Such a 3D printing machine has the advantages described above andlikewise achieves the objects underlying the application.

Furthermore, a 3D printing device disclosed herein may comprise aninsertion opening with a closure means, wherein the closure means can beopened and closed or the closure means is opened or penetrated by thefunction unit according to any one of claims 1 to 8 during retractionand extension.

In another aspect, the disclosure relates to a method for retractingor/and extending, i.e. for for changing or exchanging, an exchangeablefunction unit as described above into or out of a 3D printing device,wherein the function unit is optionally moved to the 3D printing deviceby a lifting means, optionally a crane, a lifting platform or a liftingtrolley, the function unit is inserted into the insertion opening, ispositioned at the target position in the 3D printing device and issecured by means of one or more securing means.

With such a method, it is possible for the first time to simply exchangeseveral functional units quickly and easily without the need forcomplicated adjustment work on the machine itself during the exchangeand the associated disadvantages described. Advantageously, anexchangeable function unit is used which comprises several functionalunits and which are pre-adjusted, so that time-consuming and costlyadjustment work on the machine itself is not necessary.

Further aspects of the disclosure will be described below.

In well-known 3D printing machines, print heads and coating blades areessential wear parts. In addition, there are exposure units and/orirradiation units, depending on the process.

These units must be aligned with each other within a certain frameworkfor a good print result. The coater defines the spatial position of thelayer plane and the print head should be guided at as constant adistance as possible from the layer plane.

If a single component is exchanged, it must be adjusted to therespective other components, depending on the individual configuration.Due to the size of the machines, the manufacturing accuracy of the partsin relation to each other is usually not sufficient to achieve thedesired result without adjustment.

Adjustment in the machine can also be a laborious task, as it takesplace in a confined space and accessibility is not given. In addition,the system may need to be put in a special safe set-up mode to allow anoperator to handle the units. After all, there may be process media inthe machine from which the set-up personnel must be protected.

The solution disclosed herein provides an exchangeable function unit inwhich process-relevant units can be removed as one assembly from thesystem and replaced by another pre-adjusted unit without the need to setup the units in the system relative to each other.

An exchangeable function unit can consist of at least one coater and oneor two print heads, which may additionally be movable transversely tothe coater direction via an offset axis.

The coater is a unit for dispensing fluid media such as particulatematerials, resins, slurries or pastes in a defined form onto a substrateso that a flat layer of this media of predetermined thickness is formed.A coater can be used to apply pulverulent/particulate materials.

The coater could, for example, be configured as a roller that rotates inthe opposite direction to the coating direction. A particulate materialreservoir could be added to the roller. The reservoir could, forexample, dose particulate material in front of the roller in acontrolled manner via a rotary feeder.

A further embodiment relates to an oscillating coater with a powderreservoir suspended in an oscillating manner and a gap in the lowerregion, on a side of the powder reservoir which points in the coatingdirection, said gap being as wide as the construction field. The coateralso has a drive that makes the reservoir oscillate, causing the powderto trickle out of the gap.

In one aspect, inkjet-type devices can be used as print heads, but it isalso conceivable to use selective exposure units such as lasers,projectors or mirrors via which selective irradiation units can beprojected onto the construction field. Alternatively, other devices canbe used for the transfer of information, such as toners or ink transferrollers known from laser printers or offset printing, for example.

In addition, other units such as exposure units may be attached, whichact similarly to the coater over the entire width of the unit. Theseexposure units can emit energy to the construction field, e.g. in the UVrange but also in the heat radiation range. It is also conceivable thatdrying units are attached, which work, for example, via the supply andremoval of hot air.

In addition to these components in the exchangeable function unit, it isalso conceivable, however, that the exchangeable function unit consistsof combinations of several coaters, one or more print heads and severalirradiation units.

For example, the exchangeable function unit can consist of a combinationof two coaters, each coating in one direction only, and one or moreprint heads in between to generate the layer information. In addition,one radiation source can be located on each of the coaters.

The exchangeable function unit may have a support on which the variousunits are mounted and adjusted to each other. The support may have meansfor easy reception and fixation in the layer construction system.

All media for supplying the exchangeable function unit can be easilycoupled in the system. The receptacles can be designed in such a waythat different exchangeable function units can be interchanged withoutfurther effort.

The exchange in the system can be designed in such a way that theexchangeable function unit can be moved out of the system and into thesystem via auxiliary devices without any risk of damage to the layerconstruction system as well as the exchangeable function unit. Suitableauxiliary devices are, for example, full-extension mechanisms ortransport frames with corresponding receptacles. The auxiliary devicescan be permanently installed on the machine or can be inserted asrequired. In another embodiment, the exchangeable function unit isextended out of and retracted into the 3D printer via an industrialrobot.

The auxiliary devices or transport devices are designed in such a waythat the process unit can be moved for further use or maintenance withsimple means of transport such as a trolley, forklift or crane after ithas been removed from the layer construction system.

In the system itself, traversing axes are mounted in such a way thatthey can easily pick up the exchangeable function unit and move itacross the construction field. Preferably, only one pair of axes isrequired for this, which is located parallel to the coating direction oneach side of the construction field.

In one embodiment, the exchangeable function unit is moved from onereversal position to the other and produces a fully processed layerduring this movement.

The machine may also have maintenance units that affect parts of theexchangeable functional unit and that also need to be approached fromtime to time. This can be, for example, a print head cleaning stationand/or a recoater cleaning station. In alternative embodiments, suchmaintenance units could also be mounted on the exchangeable functionunit and exchanged with it.

The system also has units for supplying the exchangeable function unitwith media, such as powder materials, inks and energy.

The exchangeable function unit can also have data processing units,control assemblies and sensors such as a print head controller, signalinterfaces/fieldbus elements, electric/pneumatic valves and a widevariety of sensors for monitoring the unit and process states.

The exchangeable function unit can, for example, have various sensorsfor monitoring the layer construction process. A sensor could be, forexample, a camera in line form, where the image of the processed layeris created by moving the process unit.

The assembly and adjustment of the exchangeable function unit is carriedout outside the layer construction system. For this purpose, devices arepreferably provided which facilitate assembly, disassembly, inspectionand, in particular, adjustment of the units on the support of theexchangeable function unit. In particular, the support and theconstruction field tools are designed in such a way that they can beinstalled or exchanged independently of the other construction fieldtools.

In another aspect, the material supply in the recoater may be sufficientfor at least one layer.

To minimize component defects, there may be a horizontal offset axis forthe print head that shifts nozzles transversely to the coating directionin a specific or random manner after each or several layers.

The pre-adjustment options can be selected in a variety of waysdepending on the requirements of the processes and materials.

Pre-adjustment options may include:

-   -   the possibility of adjusting the recoaters to each other,    -   the possibility of adjusting the process unit to the machine        frame of the 3D printing machine,    -   optionally, a line scan camera for process monitoring,    -   adjustment possibilities within the process unit,    -   the print head is adjustable perpendicular to the placement        surface,    -   the recoater is adjustable in parallel alignment and height to        the construction field,    -   the recoater is adjustable individually and/or at an angle to        the construction field,    -   the sensor system for monitoring the unit and the process is        adjustable,    -   the lamp(s) is/are adjustable to the construction field.

Furthermore, quick couplings for all media and lines, suitable shut-offvalves allowing to hold back the printing media, and adaptable voltageregulators to adapt the printing module control can be combined with theexchangeable function unit.

Furthermore, it is possible to work within advantageous tolerances, e.g.0.01 to 0.05, preferably of 0.03 mm, for accuracy or/and parallelalignment.

In one aspect, an exchangeable function unit may be provided with adouble-acting recoater in the center and two print heads. The recoatercan be mounted in the exchangeable function unit in a vibration-freemanner.

In one aspect, the recoater could be arranged upside down (recoater gapfacing out) and this could allow the print and recoating image of eachlayer to be visible and facilitate quality assurance. For example, onecould then take a photo of each layer from above and evaluate it usingimage processing software. The passive recoater must then be able to belifted by means of suitable actuators so that the layer just applied isnot damaged.

In one aspect of the present disclosure, the exchange-able function unitcan be arranged on a gantry by means of 4 combined receiving andsecuring means. In this way, it can be achieved that the pre-assembledfunction units and in particular the recoater and the print head(s)adopt an advantageous alignment not only with respect to each other butalso with respect to the construction plane, thus meeting high qualityrequirements.

In one aspect, the receiving and securing means with degrees of freedom,together with a receiving and securing means without degrees of freedom,prevent static overdetermination of the function unit in the machine andalso allow for thermal expansion effects. This advantageously preventstensioning of the function unit and a resulting change in position

In addition, the symmetrical arrangement of the receiving means enablesequal stiffnesses both in the machine and in the function unit in orderto absorb the process forces as far as possible without distortion andthus without positional changes.

The degrees of freedom can also be interchanged and do not necessarilyhave to be arranged/executed in this configuration.

In one aspect, at least 3 receiving means are useful to ensure thecorrect orientation of the function unit in the machine in terms ofposition and location. in addition, at least 1 securing means can beused, or at least 1 of the 3 receiving means can be embodied as acombined receiving and securing means.

In a further aspect, the receiving means may be any centering and forcereceiving means commonly used in mechanics. These include, for example,but are not exclusive to, centering pins, bearing surfaces, bolts,centering balls, lead-in chamfers. AH fixing mechanisms commonly used inmechanics can serve as securing means, both manually operated andautomated. These include, for example, but are not exclusive to, toggleclamps, swing clamps, latches, ball lock pins, damping bushes.

In particular, according to the present disclosure, easy replacement ofwear parts without downtime of the 3D printing machine can be achieved.

In the exchangeable function unit (1) according to the presentdisclosure, the print head and recoater axes are pre-adjusted to eachother without requiring further adjustment after placement in the 3Dprinting machine. Advantageously, the X and Y axes are pre-adjusted toeach other outside the 3D printing machine.

In one aspect, certain dimensions and ratios of the machine parts may beadvantageous, as described below.

With the exchangeable process unit according to the present disclosure,advantageous centering accuracies of the receiving means can also beachieved, which have a positive effect on the 3D printing process.

A minimum requirement may be as follows;

±half the resolution of the material application means; potentiallyadvantageous: more accurate than ± 1/10 of the resolution of thematerial application means, but not more accurate than ±1 μm.

An exemplary machine can work as follows:

Print resolution=200 dpi=127 μm-> 1/10 of 127 μm=127 μm. Thus, apreferred centering accuracy is better than ±12.7 μm. This results in acentering accuracy of ±5 μm for the components used.

Exemplary height tolerance of the levelling coater elements (blade,roller or coating knife) in the direction of the construction fieldnormal at any measuring point along the coater width:

Exemplary minimum requirement: <±33% of the layer thickness.

Potentially advantageous: <±20% of the layer thickness, or <±10% of thelayer thickness.

An exemplary spacing of the levelling coater elements of several coatersin the direction of the construction field normal at any measuring pointalong the coater width within an exchangeable function unit is asfollows:

Exemplary minimum requirement: <±20% of the layer thickness

Potentially advantageous: <±10% of the layer thickness

An exemplary machine can work as follows:

Layer thickness 280 μm->perpendicular dimensional tolerance of therecoater blades to each other at any measuring point along the blade:±20 μm (corresponds to 7% of the layer thickness).

When using a print head as a material application means: The print headis orthogonal to the direction of movement of the function unit (withthe surface normal of the construction field as the imaginary axis ofrotation).

An example minimum requirement: <±5‰ of the print width. Potentiallyadvantageous: <±1‰ of the print width, or <±0.1‰ of the print width.

An exemplary machine can work as follows:

Print width=1,300 mm->allowed rotation of the print head around theperpendicular line ±0.1 mm/1,300 mm (corresponds to 0.08‰).

Exemplary Description of the Disclosure

Various aspects of the disclosure will be described below by way ofexample, without being construed as restrictive. Also, any aspect fromthe example figures shown below can be made usable in any combination.

FIG. 1 shows an exchangeable function unit (1) in two differentembodiments. In FIG. 1A, the exchangeable function unit (1) has tworecoaters (2) mounted on the left and right of a print head (3) in thecoating direction. In addition, the exchangeable function unit hasfurther layer treatment means such as IR radiators (4), which are alsoprovided on both sides. If the print head in this arrangement has anozzle distribution that is as wide as the construction field, a layercan be processed in one pass. The embodiment shown in FIG. 1B only hasone recoater (2) and a print head (3). The advantages of theexchangeable function unit can also be used in this configuration.Furthermore, the exchangeable function unit (1) has a radiation sourceas a layer treatment means (4). In both embodiments, the constructionfield tools are connected to each other by means of a plate as aconnecting means (5). Securing means (7) are attached to the plate (5)using which securing means (7) the exchangeable function unit (1)assumes a defined position and orientation in the 3D printing machine atthe target position.

FIG. 2 shows a schematic representation of a 3D printing machine (6).Securing means (7) for the exchangeable function unit (1) are shown atthe target position, to which the exchangeable function unit (1) withits counterparts (7′) can be coupled. The traversing axes for theexchangeable function unit have already been brought into the removalposition. The exchangeable function unit is detachably coupled to anenergy and media supply (8).

FIG. 3 shows the exchangeable function unit (1) fixed in the targetposition via receiving and securing means (7, 7′) and coupled to theenergy and media supply (8).

FIG. 4 schematically shows the retraction of the exchangeable functionunit (1) into a 3D printing machine (6). For this purpose, theexchangeable function unit (1) can be retracted into the 3D printingmachine via the insertion opening (9). To this end, the closure means(10) are opened and closed again after retraction. After reaching thetarget position, the exchangeable function unit (1) is secured in thetarget position by receiving and securing means (7, 7′).

FIG. 5 shows an exchangeable function unit (1B) passing in one directionduring the printing process.

FIG. 6 schematically shows a printing pass of an exchangeable functionunit (1A) in one direction (Part 6A) and in the opposite direction (Part6B). The structure of a print layer is clearly visible.

FIGS. 7-9 show the above-described embodiments of the arrangement of theexchangeable function unit on a gantry by means of 4 combined receivingand securing means.

In particular, FIG. 9 shows the degrees of freedom provided in the 4receiving and securing means so that any function unit can always bereceived in the correct position and location. Here, the receiving andsecuring means without degrees of freedom (without arrows) defines theposition of the function unit in the machine. The receiving and securingmeans with one degree of freedom (1 arrow) prevents the rotation of thefunction unit around the first receiving and securing means as a pivotpoint. This second receiving and securing means thus partly defines theposition of the function unit in the machine. The two receiving andsecuring means with 2 degrees of freedom (2 crossed arrows) prevent thefunction unit from tilting (twisting) around the imaginary axis betweenthe first and second receiving and securing means. They thus completethe position definition of the function unit in the machine.

The receiving and securing means with degrees of freedom, together witha receiving and securing means without degrees of freedom, prevent thestatic overdetermination of the function unit in the machine and alsoallow for thermal expansion effects. This prevents tensioning of thefunction unit and a resulting change in position.

In addition, the symmetrical arrangement of the receiving means enablesequal stiffnesses both in the machine and in the function unit in orderto absorb the process forces as far as possible without distortion andthus without positional changes.

The degrees of freedom can also be interchanged and do not necessarilyhave to be arranged/embodied in this configuration.

FIGS. 10 to 12 show a further embodiment of the number and arrangementof the receiving and securing means. There is no need to use 4 pieces.At least 3 receiving means are useful to ensure the orientation of thefunction unit in the machine in the correct position and location. Inaddition, at least 1 securing means must be used, or at least 1 of the 3receiving means can be configured as a combined receiving and securingmeans. The Figures show 3 combined receiving and securing means.

FIGS. 13 and 14 show an embodiment of the invention wherein thereceiving means and securing means of the exchange-able function unitare separate from one another. The correct position and location of thefunction unit within the machine is ensured by the receiving means. Thesecuring means then ensure that this orientation in the correct positionand location is maintained and is not changed, for example, by theacceleration forces and vibrations that usually act on the function unitin the machine during operation. The receiving means may be anycentering and force receiving means commonly used in mechanics. Theseinclude, for example, but are not exclusive to, centering pins, bearingsurfaces, bolts, centering balls, lead-in chamfers. All fixingmechanisms commonly used in mechanics can serve as securing means, bothmanually operated and automated. These include, for example, but are notexclusive to, toggle damps, swing damps, latches, bail lock pins,clamping bushes.

LIST OF REFERENCE NUMERALS

-   -   1 exchangeable function unit    -   2 material application and/or smoothing means    -   3 means for selective solidificaion    -   4 optional layer treatment means    -   5 connecting means    -   6 device for 3D printing    -   7 receiving means and/or securing means    -   8 energy supply of the exchangeable function unit    -   9 insertion opening    -   10 closure means    -   11 translational degrees of freedom of the receiving means        and/or securing means    -   20 rail (e.g., parallel to coating direction)    -   22 gantry (e.g., including traversing axes)

1. A 3D printing device comprising: i) a 3D printing machine includingtwo parallel rails; ii an exchangeable function unit; and iii) at leastthree combined receiving and securing means for removably arranging theexchangeable function unit over the rails; wherein the exchangeablefunction unit comprises at least two functional subunits including atleast one recoater, least one printhead, and optionally at least one IRradiator; wherein the functional subunits are mechanically connected toeach other, directly or by a connecting means. 2-19. (canceled)
 20. The3D printing device of claim 1, wherein the two rails include a firstrail and a second rail, the at least three combined receiving andsecuring means includes a receiving and securing means positioned overthe first rail and a receiving and securing means positioned over thesecond rail.
 21. The 3D printing device of claim 1, wherein thereceiving and securing means includes one or more of a quick releasefastener, a magnet, a snap fastener, or an electromagnetic fastener. 22.The 3D printing device of claim 1, wherein the 3D printing machine has aclosable insertion opening for receiving the exchangeable function unit.23. The 3D printing device of claim 20, wherein the exchangeablefunction unit includes a gantry.
 24. The 3D printing device of claim 23,wherein the gantry includes a first gantry portion for securing to thefirst rail and a second gantry portion for securing to the second rail.25. The 3D printing device of claim 24, wherein the first gantry portionand the second gantry portion are generally parallel to the first andsecond rails.
 26. The 3D printing device of claim 25, wherein theprinting device includes two of the receiving and securing means overthe first rail for securing the exchangeable functional unit to thefirst rail; and/or the printing device includes two of the receiving andsecuring means over the second rail for securing the exchangeablefunctional unit to the second rail.
 27. The 3D printing device of claim23, wherein the gantry includes a transverse portion that is generallyperpendicular to the first and second rails.
 28. The 3D printing deviceof claim 27, wherein one of the receiving and securing means attaches tothe transverse portion of the gantry.
 29. The 3D printing device ofclaim 23, wherein the gantry rides on the rails and the receiving andsecuring means secures the exchangeable function unit to the gantry. 30.The 3D printing device of claim 29, wherein the gantry includes one ormore first portions that move over the first rail and one or more secondportions that move over the second rail.
 31. The 3D printing device ofclaim 30, wherein the gantry includes a transverse portion that isgenerally perpendicular to the rails.
 32. The 3D printing device ofclaim 31, wherein one of the receiving and securing means secures theexchangeable function unit to the transverse portion of the gantry. 33.The 3D printing device of claim 1, wherein the exchangeable functionunit includes the connecting means.
 34. The 3D printing device of claim33, wherein the connecting means includes a connecting plate.
 35. The 3Dprinting device of claim 34, wherein the printing machine includes aplatform and the recoater deposits particulate material in layers on theplatform, and the printhead extends a width of the platform.
 36. The 3Dprinting device of claim 35, wherein the printing machine has a closedprocess chamber.
 37. The 3D printing device of claim 1, wherein i) atleast one recoater includes a first recoater and a second recoater, andthe at least one print head includes a print head between the first andsecond recoaters; and/or ii) at last one print head includes a firstprint head and a second print head, and the at least one recoaterincludes a recoater between the first and second print heads.
 38. The 3Dprinting device of claim 22, wherein the insertion opening includes aclosure that is automatically opened and closed.
 39. A 3D printingdevice comprising: i) a 3D printing machine including two parallelrails; ii) an exchangeable function unit; and iii) multiple receivingand securing means for removably arranging the exchangeable functionunit over the rails; wherein the exchangeable function unit comprises atleast two functional subunits including at least one recoater and atleast one printhead, wherein the functional subunits are mechanicallyconnected to each other, directly or by a connecting means.
 40. The 3Dprinting device of claim 39, wherein the multiple receiving and securingmeans includes a receiving and securing means having no degrees offreedom.
 41. The 3D printing device of claim 39, wherein the multiplereceiving and securing means includes a receiving and securing meanshaving one or two degrees of freedom.